Electron-discharge apparatus



J. C. WARNER ELECTRON DISCHARGE APPARATUS Jan. 5, 1926. v 1,568,701

Filed March 5 1925 Inventor:

John C.Wa1-ner;

His Anbornes.

Patented Jan. 5, 1926.

UNITED STATES 1,568,701 PATENT OFFICE.

JOHN C. WARNER, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRON-DISCHARGE APPARATUS.

Application filed March 5, 1925. Serial No. 13,042.

To all whom it may concern:

Be it known that I, JOHN C. VARNER, a citizen of the United States, residing in Schenectady, in thecounty of Schenectady, State of New York, have invented certain new and useful Improvements in Electron- Discharge Apparatus, of which the followin is a specification.

y present invention relates to electron discharge apparatus, and more particularly to the operation of devices of the thermionic type having at least four electrodes.

One of the objectsof my invention is to provide improved circuit organizations whereby devices of the type mentioned may be more particularly adapted for the production of oscillations.

In connection with electron discharge devices of the thermionic type having a grid for controlling the flow 0 current between cathode and anode, it has been proposed to em 10 a second grid between the cathode and tile control grid and to impress upon this second grid a constant positive potential somewhat lower than that of the anode. A grid used in this way is commonly known as a space charge grld. The purpose of this grid is to lower the impedance between the cathode and anode, and for this purpose the grid has ordinarily been maintained at a constant positive potential.

When such a device is used for the purpose of producing oscillations or for other purposes where the anode current may at times fall to a low value, it is not necessary to maintain the positive potential on the space charge grid at all times, it being sufiiclent for all practical purposes merely to have the desired positive potential on the grid at times when the current flowing to the anode is comparatively large. When the s ace charge grid is positive all the time it is drawing current and consuming energy.

A more specific ob'ect of my invention is to provide a means or automatically varying the potential of the space charge grid in such a way that it will be of such a positive value as to appreciably lower the impedance of the device only when the current flowing through the anode is appreciably above its minimum value. At other times the space charge glrid may be maintained at zero potential wit respect to the cathode or even at a negative potential without interfering with the satisfactory operation of the device, and by this expedient the losses in the system may be reduced and the efficiency thereby increased.

Still another object of my invention is to provide a means for efliciently interrupting the production of oscillations by a device of the type mentioned for the purpose of signalling,

- The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, both as to its organization and method of ope-ration, will best be understood by reference to the following description taken in connection with the accompanying drawing, in which Figs.

1, 2, and 3 illustrate diagrammatically three different circuit organizations whereby my invention ma be carried into effect.

I have indlcated in the drawing by conventional symbols an electron discharge device 1, having the usual electron emitting cathode 2, anode 3, a discharge control grid 4 and a space grid 5. In the system shown in Fig. 1 an oscillating circuit comprising inductances 6 and 7, and capacities 8 and 9, is connected between the anode and the discharge control grid. The inductance 6 of the oscillatingcircuit is variably coupled to a load circuit 10 and to a coil 11, which is included in the circuit between the cathode and the space charge grid 5. By this means a voltage is impressed upon the space charge grid, which is in phase with the voltage of the control grid. In this way the space charge grid'is made positive at the time when the maximum plate current is flowing. The plate impedance is thus reduced 'by a reduction of the space charge between cathode and anode. During that part of the cycle when the plate current is low, the space charge grid is negative and thus does not absorb any power.

In Fig. 2a similar arrangement is shown, but in this case the main oscillating circuit, made up of inductance 12 and capacity 13, is coupled by the variable couplings 14, 15 and 16 to the plate circuit and to both of the grid circuits.

The mean potential of either grid may be varied by suitable battery bias Or grid leak bias, as may be required to secure the most 'efiicient operation of the particular .tube employed.

The space charge grid, when employed in the manner indicated, also has other advantages in addition to the neutralization of space charge. In a power tube which has a low plate impedance, the plate current for signalling purposes. This may be accompllshed by means of a key associated with the circuit of the space charge grid. In-Fig. 1 I have shown the key 17 so arranged that it opens the circuit of the space charge grid. This will raise the impedance of the output to such a value that oscillations will be interrupted. In the arrangement shown in Fig. 2 the key 17 is so located that it short circuits the inductance in the circuit of the space charge grid, and thereby causes a high increase in the impedance of the output and interrupts the production of oscillations.

While it will usually be preferable to employ the grid nearest the cathode as the space charge grid, devices of the type here under consideration may be operated in much the same manner with the grid near- -est the anode employed as an auxiliary grid and the grid nearest the cathode as control grid. The arrangement in Fig. 3 shows the connections made in this manner, the circuit otherwise being arranged in the same way as the circuit shown in Fig. 1.

While I have shown and described the preferred embodiments of my invention, it will be apparent that many modifications in the circuit arrangement can be made without departing from the scope of my invention as set forth in the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is 1. The combination with an electron discharge device having an electron emitting cathode, an anode and two grids interposed between cathode and anode, one of said grids being nearer the anode than the other, of means for producing oscillations comprising an oscillating circuit connected to the anode and one of the grids and a coupling between the oscillating circuit and a circuit of the other grid.

2. The combination with an electron discharge device having an electron emittin cathode, an anode and two grids interpose between cathode and anode, one of said grids being nearer the anode than the other, of means for producing oscillations comprising an oscillating circuit connected to the anode and one of the grids and a coupling between the oscillating circuit and a circuit of the other grid, and means associated with the circuit of the other grid for interrupting the production of oscillations.

3. The combination with an electron discharge device having an electron emitting cathode, an anode and two grids interposed between cathode and anode, one of said grids being nearer the anode than the other, of means for producing oscillations comprising an oscillating circuit associated with the anode and one of the grids and a coupling between the oscillating circuit and a circuit of the other grid.

4. The combination with an electron discharge device having an electron emitting cathode, an anode and two grids interposed between cathode and anode, one of said grids being nearer the anode than the other, of means for producing oscillations comprising an oscillating circuit associated with the anode and one of the grids and a coupling between the oscillating circuit and a circuit of the other grid, and means associated with the circuit of the other grid for interrupting the production of oscillations.

5. The combination with an electron discharge device having an electron emitting cathode, an anode and two grids interposed between cathode and anode, one of said grids being nearer the anodethan the other, of means for producing oscillations, comprising an oscillating circuit connected to the anode and the grid nearest the anode and a coupling between the oscillating circuit and a circuit of the grid nearest the cathode,

6. The combination with an electron discharge device having an electron emitting cathode, an anode and two grids interposed between cathode and anode, one of said grids being nearer the anode than the other, of means for producing oscillations, comprising an oscillating circuit connected to the anode and the. grid nearest the anode, a coupling between the oscillating circuit and a circuit of the grid nearest the cathode, and means associated with the circuit of the grid nearest the cathode for interrupting the production of oscillations.

In witness whereof, I have hereunto set my hand this 3rd day of March, 1925.

JOHN C. WARNER. 

